A very determined boy being bullied at school forms an unbreakable bond with a wild brumby stallion in 1895 Australia. Casey just immigrated from America. At first, he hates Australia. He works to earn his horse Lady, then enters her in a race to save Moonrunner's life. Lady must winter with the wild brumby because they have no money for feed. Moonrunner shows Casey how to love the wild country called around the Mitta Mitta River.